Core extractor



C. LAMB CORE EXTRACTOR Filed NOV. 12, 1946 Nov. 7, 1950 CHAQLE'LS LAMB,

v m/va/rae Patented Nov. 7, 1950 Charles Lamb, South Pasadena, Calif., assigno'r to Zelarn Rubber Cement Plug 00., Los Angeles,

Calif-., a partnership Application November 12, 1946, Serial No. 709,320

This invention relates to sealing plugs and core extractors of a type which may be used in extracting a sample of material from a geologi cal coring barrel or the like as ordinarily em ployed in oil well or similar drilling operations, and more particularly to a-sealing plug or core extractor of improved construction associated with a new and improved means and material for constructing the same.

Ordinarily, in oil well drilling and similar operations it is desirable toobtain a sample of a selected section of the strata through which the drilling is progressing in order that the operator may be in a position to assess the value of a proposed shaft or the nature and location of any oil or mineral. Similar cores are often taken to sample agricultural and other land. Moreover, it is important to provide a suitable member for capping or cementing off oil wells or other conduit systems. During'coring operations, for

example, a string of pipe is usually 'sunkor driven" tea desired depth but on orbefore reaching such depth a section of pipe conventionallyknown as a core barrel is driven into the ground and forced full of the material of which a sample is desired to be taken. Such sample or core, particularly in hard strata, generally comprises a plug of earth and/r rock firmly driven into and confined within the interior of the core barrel, and is removed by the application of pressure at one end of the barrel to force'the core out of the other end. 1

For this purpose it is customary to cap one end 2' is highly resistant to shock, is eminently to be desired.

Obviously a relatively hard leading end is 'desired on the, plug for engagement with the core 2 whereas ayrelatively softer, more resilient trailing end is to be preferred so that this latter end may be wedged laterally against the inside walls of the corebarrel making a sealing fit therewith and forcing all of the material out ahead of the core and also ahead of any fluid used for extract= ing the same. Unless such aconstruction is provided, the leading end of the core remover, if soft, will wedge and jam against the walls of the barrel, and the trailing edge, if hard, will not furnish a proper seal. "Previous attempts to form a desired plug of synthetic rubber material with a relatively hard leading end and relatively soft trailing end have not been completely satisfacof the barrel and admit a fluid under pressure which enters a port in said cap forcing the core material ahead of it. It may be readily understood that unless a suitable plug-like member is positioned ahead of the fluid a mis-shapen core is often forced out in a manner destructive of the relative positions of various superimposed layersof earthen material. The proper and de- .sired juxtaposition of the'material is retained only if the plug forces substantially the entire imized and a seal may be formed to force the plug ahead of the entering fluid. The combina tory, because the bond between the two sections could notbe made sufliciently permanent.

Applicant has found, however, that by the proper proportioning o'f certain suitable rubbery and resinous materials the desired variant hardness of the parts of a core extractor, cementing plug, or piston having a tenacious and permanent bond may be obtained in a simple and effective manner and with an economy of manufacture not heretofore thought possible.

It is therefore an object of this invention to provide a unitary plug having a relatively hard, incompressible leading end and a relatively soft, compressible trailing end.

It is another object 'to provide a core extractor or sealing plug of the character described having a suitably shaped trailing" end adapted to be firmly forced against the inner walls of a core barrel orpipe while being directed forwardly in Another object is to "provide an improved method of producing core extractorsand similar articles containing adjacent portions of synthetic tion, therefore, of a unitary plug, the parts of which are smooth and simply constructed, to avoid the entrance of foreign material such as oil, earth, and the like, which therefore avoids any tendency to pollute the sample, and which rubber of varying resilience or hardness.

A further object is to provide a novel combination of rubbery substances fromv a designated group and a resinous material which is compatible therewith in'a manner permit-ting'the firm coherence of different portions of said rubber-like material in varying proportions;

Another object is to provide a new and im- V proved inethod of producing synthetic rubber materials having connected sections'of substantiallyeny desired degree of varying hardness which sectionsare none-the-les's firmly coherent 3 when forced together and cured under heat and pressure.

Yet another object is to provide a suitable, preservative, anti-oxidantand binding agent for synthetic rubber products.

It is also an object to provide an economical and effective core extractor and plug embodying improvements over prior art devices and methods utilized for the same purpose.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device and of the method steps practiced whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in the claims and illustrated in the accompanying drawings.

In the drawings:

Figure l is a vertical sectional view of a typical core barrel showing the disposition of a core and a core extractor of a'type contemplated by this invention disposed therein. I

Figure 2 is an elevational view partially in section of the core extractor.

Figure 3 is a plan view of the same. 7

Figure 4 is a sectional elevational view of a typical molding cavity illustrating a preferred method of production of the core extractor.

. Referring more particularly to the drawings, a core extractor, also suitable for use as a sealing or cementing plug, or piston, generally designated by the numeral l0, comprises a cylindrical leading end [I and a substantially cup-shaped trailing end l2 having a more or less distinct area of fusion or coherence l5 therebetween.

In its preferred form said trailing end is formed with an axially disposed cup-shaped cavity [6. At its rearmost trailing edge I! the extractor is formed with a flange or lip 18 of substantially greater thickness at its rearmost portion than its foremost portion 19 to provide a substantial bearing surface against the walls of a pipe or core barrel 20. The trailing-end of the core extractor forward of the flange I8 is tapered out wardly to give the trailing end a diameter slightly greater than the leading end. A desirable difference in diameter between the leading and trailing ends has been found to be approximately in a core extractor, piston, or plug, having a leading end of from one to two inches in diameter, although this figure and proportion is subject to variation depending upon the nature of the work to be performed including the characteristics of the core and in some cases the diameter as related to the material of which the core barrel may be made. 7

In the use of the extractor a string of pipe sometimes incorporating a separable core ,barrel may be run in a manner to obtain a desired core 2! of earthen material therein. The barrel'is first removed from a string of pipe (not shown) and the core extractor placed in the top of the core barrel which is devoid of vthe core for'a sufficient portion of its length to accommodate the extractor. After the positioning of the extractor therein, the barrel may be fitted with a cap -22 into which is threaded any suitable pipe fitting, such as an elbow 23 secured to any desired conduit 25 and connected to a source (not shown) of fluid under pressure preferably air.

Said fluid is admitted into thetop of thecore barrel, whence it enters the cavity H5 in the trailing end of the extractor forcing the flange l8 against the innerwalls of the barrel to seal the same and moving the extractor forwardly against the core. For this purpose the trailing end of the extractor is preferably made of a rubber-like synthetic composition, as hereinafter set forth, substantially softer than that of the leading end H which is of the same general composition but compounded to cure hard.

In the production of a core extractor of the desired type, caoutchouc-like ingredients of the type of Buna S (butadiene-styrene copolymer), Neoprene (chloroprene polymer), Buna N (butadiene-acrylonitrile copolymer), Butyl (isobutylene-diolefin copolymer), have been found most suitable. To any one of the designated materials in their uncured state approximately 10% by weight of a urea-formaldehyde or phenol-formaldehyde thermo-setting type resin is added in order to form the trailing end of the extractor of a desired relative firmness. This stated percentage of resin has been found to harden the above-named synthetic materials to a desired extent while at the same time rendering them sufficiently soft and resilient for proper deformation when subjected to pressure. It has been found that the addition of greater percentages of resin, as for example up to over 60% by weight, to said rubber-like materials in their prevulcanized state results in corresponding compositions of progressively greater hardness. An addition of approximately 60% of the phenol-formaldehyde provides a leading end of the core extractor of suitable hardness for the purpose intended.

A thermo-setting type of synthetic resin as, for example, urea-formaldehyde or phenol-formaldehyde resin, combined with one of the three above-named preferred forms of rubber-like material gives a final product having a hardness roughly corresponding to the percentage of resin mixed with the raw material. Such formaldehyde resin, as illustrated by one commercially available under the trade name Durez, is susceptible of being cured within substantially the same range of temperatures and pressures as the synthetic rubbery mass. For example, a phenolformaldehyde resin having no filler may be suitably cured by compression molding under a pressure of approximately 2,000 to 3,000 pounds per square inch at a temperature at from 300 F. to 400 F. and the rubbery material may be cured within substantially the range of 260 F. to 350 F. at molding pressures varying from approximately 2,000 to 6,000 pounds per square inch. While the use of the phenol-formaldehyde having no filler is preferred, this resin may optionally contain any of the conventional fillers such as woodflour, mineral, macerated fabric, sisal felt, paper, cotton, glass, asbestos, wood, or the like.

A preferred and economical method of forming the extractor includes the steps of separately mixing the above-named percentages of preferred rubber-like material and raw phenol-formaldehyde, extruding each of the batches of ma- 'terialsso mixed in the form of separate rod-like preferably cylindrical bars, then cutting the bars so formed into desired approximate half-lengths relative to the size of the core extractor intended to be produced. The half-portion of extruded material containing the greater percentage of resin may then be placed in the bottom of a suitably shaped mold 126, and the material containing the lesser percentage of resin positioned within said mold above the first material and in contact therewith. Upon application of the desired curing pressure, with the aid of the required amount of heat, as with'the aid of a molding ele- S ment 26 havin substantially the shape of the cup-like cavity l6 desired, simultaneous curing, forming, and bonding of the adjacent halves occurs. It has been found that the bond so formedis sufficiently strong to resist any attempt to. pull the. finished article apart without rupturmg the rubbery material upon either side of the fusion line and whereas the more flexible trailing end may be readily spread, stretched or deformed, the leading end containing approximately 60% of said resinous material is incompressible at a normal working pressure, usually not to exceed 2200 pounds per square inch, and has tested as high as 14,000 pounds. Hence a greater amount of compression is acquired which makes for greater effectiveness, for example, in the cementing of oil wells or extracting cores for geological tests than has heretofore been obtained.

Inasmuch as densities can be made to vary from extremely hard to extremely soft by the mere addition of suitable amounts of resin, the rubbery compounds so secured are susceptible of easy handling by conventional factory procedures and equipment in modes which avoid many of the well-known difficulties usually incident to the production and handling of hard rubber compositions.

It is important to note that rubber, particularly synthetic rubber-like material of the type of which it is intended to construct a core extractor, piston, or block, for example, which requires a very hard section to provide stability and withstand high-duty pressure, must be tenaciously bonded to a soft section which provides for expansion and a sealing function. The presence of the resinous material herein noted .in both the hard and soft compositions contributes a pos-, itive interlocking or bonding feature. Without the resin in both of these sections they tend to pull apart.

Several desirable features of the thermo-setting resin, above mentioned, include its ability to blend readily with the synthetic rubbers above noted in a manner to increase the stiffness, strength, resistance to abrasion and undesired chemical action of oil and the like upon the vulcanized rubber compositions. Moreover, these resins function not merely as fillers but as reinforcing and binding pigments taking the place, in this respect, of such materials as carbon black, zinc oxide and other commonly utilized reinforcing pigments which fail as proper binding agents for synthetic rubber parts of varying density.

It should also be noted that vulcanized rubber, particularly synthetic rubber, tends to deteriorate rather rapidly in the atmosphere and must be preserved with anti-oxidants. Accordingly, it has been observed, particularly in shipments which have heretofore been made to the tropics, that a considerable deterioration of the ingredients of those objects made from synthetic materials takes place. The addition, however, of these resinous materials has made it possible to dispense with the ordinary precautions heretofore required in the course of such shipments inasmuch as it has been found that these materials act as preservatives and anti-oxidants, preservingthe snap and resilience and other desirable qualities of the synthetic rubber. The discovery of these anti-oxidizing and binding qualities of resin and their application to the-rubbery materials as above noted constitutes a valuable part of this invention.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferredembodiment'it is recognized that departures may be made therefrom within the scope of the invention, which. is not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims 50 as to embrace any and all equivalent devices, compositions, and methods. Thus in the foregoing description applicant has selected a core extractor (also called a plug) to illustrate the method of his invention as applied to this particular article. Applicant desires, however, to emphasize the fact that his method applies to the production of other articles formed of syntethic rubber having moulded portions of differing hardness fused and bonded together in the presence of a thermosetting resin common to such portions, substantially as disclosed;

The invention having been herein described, what is claimed and sought to be secured by Letters Patent is:

1. A core extractor plug of rubber composition adapted to be inserted in a core barrel for the removal, exclusively under fluid pressure, of an earth core therein and comprising a rubber cylindrical leading end adapted to engage said earth core and a rubber trailing end of substantially cup-shaped configuration coaxially and integrally bonded to said cylindrical leading end, said cylindrical leading end comprising rubber and thermo-setting phenol formaldehyde resin and being harder for resisting compression when engaged with said earth core than said cupshaped end, the latter having lips engageable with the inner walls of the core barrel under the infiuence of fluid pressure for making a fluid-tight seal with said core barrel wall, said cup-shaped end comprising rubber and a lesser proportionate amount of thermo-setting phenol formaldehyde resin than said cylindrical end.

2. An integral core extractor plug adapted to be inserted in a core barrel and to abut against a core in said barrel to remove said core from said barrel by the application of fluid pressure behind said core extractor, said core extractor comprising a cylindrical portion including a flat end adapted to abut against said core and being formed of a homogeneous rubber composition comprising rubber and thermo-setting phenol formaldehyde resin having a hardness sufficient to resist compression under the pressure necessary to remove said core and a generally cupshaped fluid sealing end portion vulcanized directly to said cylindrical member as an integral part thereof and being formed of a homogeneous rubber composition comprising rubber and a lesser proportion of said resin than said cylindrical portion and being of sufficient resilience to permit expansion of the upper side walls thereof against the inner surface of the core barrel in fluid tight engagement therewith.

3. An integral core extractor plug adapted to be inserted in a core barrel and to abut against a core in said barrel to remove said core from said barrel by the application of fluid pressure behind said core extractor, said core extractor comprising a cylindrical portion including a fiat end adapted to abut against said core and being formed of a homogeneous rubber composition comprising butadiene-styrene and thermo-setting phenol formaldehyde resin having a hardness suflicient to resist compression under the pressure necessary to remove said core and a. generally cup-shaped fluid sealing end portion vulcanized directly to said cylindrical member as an integral part thereof and being formed of of the core barrel in fluid tight engagement therewith.

CHARLES LAMB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Kiel May 8, 1906 Number Number Name Date 1,650,017 Keniston et a1 Nov. 22, 1927 1,842,116 Rasmussen Jan. 19, 1932 1,994,072 Hardcastle Mar. 12, 1935 2,005,978 Larson et a1 June 25, 1935 2,167,747 Dyer Aug. 1, 1939 2,211,048 Bitterich Aug. 13, 1940 2,326,490 Perelson Aug. 10, 1913 2,387,181 Procter Oct. 16, 1945 OTHER REFERENCES Ser. No. 357,662, Wildschut (A. P. 0.), published Aug. 20, 1943. 

